The invention relates to a marine propulsion control system. The invention more specifically relates to a marine propulsion control system adapted to control a set of propulsion units each provided with a control unit for control of the delivered thrust by the propulsion unit and selection of gear in the case a gear unit is associated with the propulsion unit. An input command regulator is provided in the marine propulsion control system to generate inputs from a driver of the vessel. The invention particularly relates to a propulsion control system adapted to control three or more propulsion units with a reduced number of control levers.
Several propulsion control systems adapted to control a plurality of propulsion units with a reduced number of control levers, that is input signals from one control lever should be sufficient to control the delivered thrust in the case the control lever is a throttle lever or to control engagement of gears in the case the control lever is a gear selector of two or more propulsion units. Examples of such propulsion control systems are presented in U.S. Pat. No. 6,872,106 and U.S. Pat. No. 6,751,533.
U.S. Pat. No. 6,872,106 relates to a propulsion control system having a plurality of propulsion units each being controlled by an associated control unit. The associated control unit receives input command signals from control levers via a remote control central processing unit, which central processing unit is configured to receive lever position data from sensors and correlate the lever position data with motor position data in order to directly control more than one motor from a single lever. All the motors controlled by the same input lever will be controlled in identical manner unless some error prevents correct control of the motors.
U.S. Pat. No. 6,751,533 relates to a propulsion control system for a vessel, which in a single embodiment described in relation to FIG. 4 controls a plurality of motors by a single control head. Each throttle lever is connected to a control unit providing control over two motors. All the motors controlled by the same input lever will be controlled in identical manner unless some error prevents. correct control of the motors. The control system according to U.S. Pat. No. 6,751,533 furthermore provides for a synchronisation mode when a master control unit commands a slave control unit to adapt its associated motor or motors to the same percentage of throttle as the motor or motors associated with the master unit. The architecture of the control system is such that there is no difference in configuration between the master control unit and the slave control unit. Each control unit may assume the role of the slave or master depending on the control of the driver. Entry into synchronisation mode is made by setting the control levers of both control units into approximately the same position, where after one of the control units assumes the role of the master control unit and the other assumes the role of the slave unit. In this mode the control lever of the throttle associated with the master control unit controls the throttle of the motor associated with slave control unit such that both motors assumes the same throttle lever. The synchronisation mode does not obviate the need for a control lever for the slave unit since this is a particular mode when the motors should have the same throttle lever. Thus independently of the whether the synchronisation node is assumed or not, all the motors controlled by the same input lever will be controlled in identical manner unless some error prevents correct control of the motors.
It is desirable to provide a marine propulsion control system which enables an adapted control of a plurality of propulsion units controlled by a single input lever such that two propulsion units controlled by the same lever may assume different levels of thrust depending on the driving situation of the vessel.
An aspect of the invention contemplates to arrange least one control unit in a set of control units provided in the control system to act as a slave control unit in all driving conditions and to receive its input control signals from one or several master control units in said set of control units to adapt the delivered thrust of the propulsion unit associated with the slave control unit to the driving condition of the propulsion unit or units associated with the master control unit or units and in that said master control unit or units in all driving conditions receives its input control signals directly from the input command regulator. According to the invention, the slave control unit is always assigned as a slave control unit and is therefore not connected directly to an input command regulator arranged for generating a desired delivered thrust by the propulsion units in the set of propulsion units. The slave control unit therefore receives control information from the master control unit in all driving conditions and adapts the delivered thrust of the propulsion unit associated with the slave control unit to the input signal from the master control unit. The adaptation may be different under different driving conditions as will be explained in further detail below. For this reason, the slave control unit may include a thrust control generator which generates a set value for its associated propulsion unit in dependence of the input signal from the master control unit. The thrust control generator may be in the form of a map or look up table which translates input signal into a requested delivered thrust level for the associated propulsion unit.
In an embodiment of the invention the input command regulator furthermore includes a gear selector for selecting forward, reverse or neutral position of gear units associated with the propulsion units, wherein each control units is furthermore arranged to control the gear selection of the associated gear unit depending on input control signals received by the control unit, wherein the slave control unit or units are, in all driving conditions arranged to adapt the gear selection of the gear unit associated with the slave control unit to the driving condition of the propulsion unit or units associated with the master control unit or units and in that said master control unit or units in all driving conditions receives its input control signals directly from the input command regulator. By the adaptation of the gear selection of the slave control unit, it is for example possible to avoid the vessel to involuntarily increase the drift of the vessel toward one side in the event one propulsion unit does not operate properly. Furthermore docking and slow control of the vessel may be more easily achieved since engagement of forward and rear gears may be programmed to be delayed for propulsion units associated with either the slave or master unit depending on the situation or design of the vessel.
The system is particularly advantageous when the input command regulator includes a single starboard input command regulator and a single port input command regulator and said set of control units includes two master control units including a single starboard master control unit and a single port master control unit and at least one slave control unit. Preferably the slave control unit is associated with a propulsion unit positioned on the centre line of the hull and that said slave control unit receives input control signals from both master control units.
The slave control unit may be arranged to engage the associated gear unit in neutral position unless both master control units has received input command signals requesting to serve their respective gear units to engage either both in reverse or both forward gear, in which case the slave control unit is arranged to engage the associated gear unit in the same gear as both gear units associated with the master units.
In the event both master control units has received input command signals requesting to serve their respective gear units to engage either both in reverse or both forward gear, the slave control unit may be arranged to engage the associated gear unit in the selected gear at a first lower level of delivered thrust and the master control units are arranged to engage their associated gear units in the selected gear at a second higher level of delivered thrust.
In this event the first lower level preferably corresponds to zero thrust and that said second higher level is lower or equal to the number of propulsion units controlled by the slave unit divided by the total number of propulsion units in said set, where the higher level preferably corresponds to less than 10% thrust.
In a further preferred embodiment each slave control unit may be adapted to control the delivered thrust from its associated propulsion unit to an average value of a first and second level of thrust indicated by the starboard and port master control units respectively.
In another embodiment each master control unit is preferably associated at least one slave control unit receiving input control signals solely from the master control unit being associated with propulsion units arranged on the same side of the centre line as the propulsion unit associated with the master control unit.
The slave control units may be arranged such that to each master control unit is associated a slave control unit that receives input control signals from one master control unit only. In this system it is preferred that the level of thrust associated with the slave unit is set to be equal to the level of thrust associated with the master unit.
The invention also relates to a vessel including a propulsion control system as has been described above, which vessel includes three or more propulsion units.